Single thread chainstitch fittings for two thread chainstitch sewing machine

ABSTRACT

A looper and a cooperating thread loop positioner for forming single thread chainstitches which may be applied to the looper carrier and work feed dog respectively of a sewing machine adjusted to operate in the production of a two thread chainstitch seam without requiring any change in the timing of any of the sewing machine parts.

[ Aug. 21, 1973 United States Patent Kostenowczyk 1 SINGLE THREAD CHAINSTITCH FITTINGS 1,127,067 2/1915 Moffatt.......................... FOR TWO THREAD CHAlNSTITCl-l SEWING 2439-332 4/1948 =5= zelcl'u-ur'n-nun 3,301,206 1/1967 Lanzendorfer... [75] Inventor: Stanley Kostenowczyk, Cranford, 3,563,194 2/1971 Conti [73] Assignee: The Singer Company, New York, Primary Examiner-Werner H. Schroeder N.Y. Attorney-Marshall .l. Bi'een et a1.

[22] Filed: May 12, 1972 [21] Appl. No.: 252,756

ABSTRACT A looper and a cooperating thread loop positioner for [52] US. 112/199, 112/168 51 1111. D05b l/06 fmmmg smgle thread hamsmhes wh'ch may be ap plied to the looper carrier and work feed dog respec- [58] Field of Search...................... 112/53, 159, 165,

tively of a sewing machine adjusted to operate in the production of a two thread chainstitch seam without requiring any change in the timing of any of the sewing machine parts.

[56] References Cited UNITED STATES PATENTS 287,576 10/1883 Post..................... 112/199 X 3 Claims, 8 Drawing Figures SINGLE THREAD CI-IAINS'I'ITCII FITTINGS FOR TWO THREAD CHAINSTITCI'I SEWING MACHINE BACKGROUND OF THE INVENTION Both single thread chainstitch forming mechanisms as well as mechanisms for forming two thread chainstit ches are individually well known. Fittings have also been made heretofore by which a two thread chainstitch sewing machine might be converted to sewing single thread chainstitches. Where such prior conversion fittings have involved oscillating loopers, it has always been required to modify the looper carrier motion drastically in order to accommodate the conversion and such timing change is a tedious task requiring a high degree of skill on the part of the mechanic making the conversion.

BRIEF SUMMARY OF THE INVENTION It is an object of this invention to provide single thread chainstitch conversion fittings which may be applied to a two thread chainstitch sewing machine without requiring any change in timing of the sewing machine parts. The object of this invention is attained by providing a single thread chainstitch looper with special thread manipulating surfaces cooperating with a thread loop positioner which may be secured to the feed dog of a compound work feed mechanism of the sewing machine to engage and distend thread loops from the looper for penetration by the needle on a subsequent needle penetration.

DESCRIPTION OF TI-IE DRAWING A preferred form of this invention is illustratedin the accompanying drawing in which:

FIG. 1 represents a perspective view of the stitch forming elements of this invention arranged concurrently to form both a single thread chainstitch seam and a two thread chainstitch seam and including a diagrammatic representation of each of the resulting lines of stitches,

FIG. 2 is an enlarged perspective view of a looper and a loop positioner or this invention,

FIGS. 3A, 3B and 3C represent three diagrammatic views showing different positions during a typical stitch forming cycle and illustrating the synchronous timed relation of the motion of a conventional two thread chainstitch looper relatively to the sewing machine needle reciprocation, and

FIGS. 4A, 4B and 4C represent three diagrammatic views showing the conversion fittings of this invention in the same relative positions as illustrated in FIGS. 3A, 3B and 3C and indicating the manner in which single thread chainstitches are formed.

FIG. 1 illustrates a looper carrier 11, a loop spreader 12 secured on a spreader carrier 13 clamped to a spreader supporting rod 14, and a work feed dog 15 of the type which are employed in a two thread chainstitch sewing machine such as forms the subject of the US. Pat. No. 2,3l2,858 Mar. 7, I943 of F. F. Zeier to which reference may be had. The Class 300W machine manufactured by The Singer Company is constructed in accordance with the principles disclosed in the above referenced patent.

Preferably, the looper carrier 11 partakes only of oscillating movements which. in the conventional operation of this type of machine, is imparted to a two thread chainstitch forming looper 16 secured in the looper carrier 11. The two thread chainstitch forming looper 16 is provided with a thread accommodating eye 17 through which a looper thread 18 is directed.

FIGS. 3A, 3B and 3C illustrate the manner in which the two thread chainstitch forming looper l6 cooperate with the loop spreader 12, the work feed dog 15, and a needle 19 which carries a needle thread 20 in the formation of two thread chainstitches (Federal Stitch Type 401 Movements are imparted to the looper carrier 11 in what is referred to in the art as synchronous timed relation to the reciprocatory movements of the needle. By synchronous timed relation" is meant that the beak 21 of the two thread chainstitch looper 16 passes in substantially the same relationship to the eye of the needle on the forward loop seizing stroke of the looper as shown in FIG. 3A as it does on the rearward loop shedding stroke as shown in FIG. 3C.

As shown in FIGS. 3A, 3B and 3C, the loop spreader engages and distends the looper thread 18 into a bight for penetration by the needle 19 so that a two thread chainstitch will be formed.

It is pointed out the work feed dog 15 is shifted forwardly and into engagement with the work as the needle moves downwardly to penetrate the work. The work feed stroke of the work feed dog occurs while the needle is in the work, the needle and work feed dog moving together during the work feeding stroke in what is referred to in the art as a compound feed arrangement. In this invention a set of fittings is provided which may be applied to the sewing machine components described above to produce a single thread chainstitch (Federal Stitch Type 101) without requiring any alteration or change of timing of the conventional sewing machine parts. The fittings of this invention may be used together and simultaneously with the conventional two thread chainstitch fittings concurrently to produce a single thread and a two thread chainstitch seam side-by-side; or the fittings of this invention may be exchanged for the conventional fittings of a sewing machine to convert the machine into condition for producing just a single thread chainstitch seam.

The fittings of this invention, as illustrated in FIG. 2 comprise a single thread chainstitch forming looper 30 having a shank 31 adapted to be secured in the looper carrier 11 in the same manner as the conventional looper 16 is secured therein. The looper blade is formed with a butt portion 32 which extends from the shank 31 and joins a loop seizing portion 33 of substantially uniform width and terminating at the free extremity in a loop seizing beak 34. At the juncture of the loop seizing and butt portions, the looper blade is formed with a thread detaining shoulder 35 which is laterally offsetto one side of the loop seizing portion 33. A tapered recess 36 which increases in depth toward the looper beak is formed in the thread detaining shoulder and preferably opens on a surface of said thread detaining shoulder which faces the free extremity of the looper blade.

The fittings of this invention also include a thread loop positioner 40 having a shank portion 41 formed with a slot 42 adapted'to accommodate a fastening screw 43 by which the thread loop positioner may be secured beneath the work feed dog 15. The positioner is formed with a flexible thread loop positioning finger 44 terminating in a cleft throat 45. The tenninal portion of the finger 44 in which the cleft throat 45 is formed is adapted to be accommodated in the tapered recess 36 of the looper blade.

As shown in FIGS. 4A, 4B and 4C, the looper 30.0f this invention is adapted to be moved in synchronous timed relation to the movements of the needle 19 but cooperates with the needle to produce single thread chainstitches. Whereas, it is known to alter the timing of an oscillating looper drive for forming single thread chainstitches by delaying the shedding looper movement so that the butt of the looper blade is presented to the downwardly moving needle, the present invention provides for single thread chainstitch formation with a synchronous timed relation" by the provision of the thread detaining shoulder 35 and the recess 36 on the looper blade and the thread positioner on the work feed dog. The terminal portion of the finger 44 in which the cleft throat 45 is formed drops in the recess 36 as the looper partakes of shedding movement shown in FIG. 4B and, therefore, the cleft throat 45 unerringly engages a limb of the previously seized needle thread loop which is held on the thread detaining shoulder 35 of the looper. As the needle descends as shown in FIG. 4C, the thread loop positioner holds distended this previous needle thread loop for penetration by the needle thus to insure enchaining of successive loops of the single needle thread 20.

With this invention a single or a two thread chainstitch seam or both may be readily produced on a sewing machine without requiring a departure from the established timing of the machine parts with which sewing machine mechanics and technicians are familiar and reluctant to disturb.

Having set forth the nature of this invention, what is claimed herein is:

1. Single thread chainstitch forming fittings including a looper and a thread loop positioner, in which said looper includes a blade formed on the free extremity with a needle loop seizing portion of substantially uniform width terminating in a thread engaging beak, a butt portion joined to said needle loop seizing portion, a supporting shank joined to said butt portion, and a thread detaining shoulder formed at the juncture of said loop seizing and butt portions and offset laterally to one side of said needle loop seizing portion to define a surface of said thread detaining shoulder which faces said looper beak, said thread detaining shoulder being formed with a tapered recess increasing in depth toward that surface of said thread detaining shoulder which faces said looper beak, and in which said thread loop positioner includes a shank portion adapted to accommodate a fastening element, and a flexible thread loop positioning finger terminating in a thread engaging throat shaped for accommodation in the tapered recess of said looper blade thread detaining shoulder, said looper and thread loop positioner being adapted to form single thread chainstitches when secured respectively on the looper carrier and work feed dog of a two thread chainstitch sewing machine of the type having a looper carrier for a threaded looper drivingly arranged to be oscillated in synchronous timed relation with the sewing machine needle reciprocation, and a compound work feeding mechanism including a work feed dog drivingly arranged to partake of work feeding strokes during work penetration of the needle.

2. In combination with a two threaded chainstitch sewing machine of the type having a looper carrier for a threaded looper drivingly arranged to be oscillated in synchronous timed relation with the sewing machine needle reciprocation and a compound work feed mechanism including a work feed dog drivingly arranged to partake of work feeding strokes during work penetration of the needle, a single thread chainstitch forming looper including a blade formed at the free extremity with a needle loop seizing portion of substantially uniform width terminating in a thread engaging beak, a butt portion joined to said needle loop seizing portion, a supporting shank joined to said butt portion and a thread detaining shoulder formed at the juncture of said loop seizing and butt portions and offset laterally to one side of said needle loop seizing portion to define a surface of said thread detaining shoulder which faces toward said looper beak, said thread detaining shoulder being formed with a tapered recess increasing in depth toward that surface of said thread detaining shoulder which faces said looper beak, means securing said single thread chainstitch looper shank in said looper carrier for movement of said single thread chainstitch looper in synchronous timed relation with the sewing machine needle reciprocation, and a thread loop positioner secured to said work feed dog and including a flexible thread loop positioning finger terminating in a thread engaging throat accommodated in the tapered recess of said looper blade thread detaining shoulder and adapted to position thread loops on said single thread chainstitch looper for penetration by said sewing machine needle.

3. The combination as set forth in claim 2 in which both a threaded looper for the formation of a two thread chainstitch and said single thread chainstitch looper are supported by the same looper carrier and operated simultaneously in cooperation with separate sewing machine needles to produce concurrently a two thread chainstitch and a single thread chainstitch seam. t 0! k 

1. Single thread chainstitch forming fittings including a looper and a thread loop positioner, in which said looper includes a blade formed on the free extremity with a needle loop seizing portion of substantially uniform width terminating in a thread engaging beak, a butt portion joined to said needle loop seizing portion, a supporting shank joined to said butt portion, and a thread detaining shoulder formed at the juncture of said loop seizing and butt portions and offset laterally to one side of said needle loop seizing portion to define a surface of said thread detaining shoulder which faces said looper beak, said thread detaining shoulder being formed with a tapered recess increasing in depth toward that surface of said thread detaining shoulder which faces said looper beak, and in which said thread loop positioner includes a shank portion adapted to accommodate a fastening element, and a flexible thread loop positioning finger terminating in a thread engaging throat shaped for accommodation in the tapered recess of said looper blade thread detaining shoulder, said looper and thread loop positioner being adapted to form single thread chainstitches when secured respectively on the looper carrier and work feed dog of a two thread chainstitch sewing machine of the type having a looper carrier for a threaded looper drivingly arranged to be oscillated in synchronous timed relation with the sewing machine needle reciprocation, and a compound work feeding mechanism including a work feed dog drivingly arranged to partake of work feeding strokes during work penetration of the needle.
 2. In combination with a two threaded chainstitch sewing machine of the type having a looper carrier for a threaded looper drivingly arranged to be oscillated in synchronous timed relation with the sewing machine needle reciprocation and a compound work feed mechanism including a work feed dog drivingly arranged to partake of work feeding strokes during work penetration of the needle, a single thread chainstitch forming looper including a blade formed at the free extremity with a needle loop seizing portion of substantially uniform width terminating in a thread engaging beak, a butt portion joined to said needle loop seizing portion, a supporting shank joined to said butt portion and a thread detaining shoulder formed at the juncture of said loop seizing and butt portions and offset laterally to one side of said needle loop seizing portion to define a surface of said thread detaining shoulder which faces toward said looper beak, said thread detaining shoulder being formed with a tapered recess increasing in depth toward that surface of said thread detaining shoulder which faces said looper beak, means securing said single thread chainstitCh looper shank in said looper carrier for movement of said single thread chainstitch looper in synchronous timed relation with the sewing machine needle reciprocation, and a thread loop positioner secured to said work feed dog and including a flexible thread loop positioning finger terminating in a thread engaging throat accommodated in the tapered recess of said looper blade thread detaining shoulder and adapted to position thread loops on said single thread chainstitch looper for penetration by said sewing machine needle.
 3. The combination as set forth in claim 2 in which both a threaded looper for the formation of a two thread chainstitch and said single thread chainstitch looper are supported by the same looper carrier and operated simultaneously in cooperation with separate sewing machine needles to produce concurrently a two thread chainstitch and a single thread chainstitch seam. 